Pressure sensors based on piezoelectric materials, such as a lead zirconate titanate (PZT) ceramic or quartz, for example, are known. FIG. 1 shows such a monolithic piezoelectric pressure sensor 101. The latter comprises a monolithic main body 102, which consists of a homogeneous layer of a pressure-sensitive material. External electrodes 105, 108 are respectively arranged on an upper side surface 109 and a lower side surface no of the main body 102, such that the layer of the pressure-sensitive material is situated between the external electrodes 105, 108. The external electrodes 105, 108 serve for tapping off the electrical signal that arises in the event of pressure loading.
In the case of the sensor 101, the pressure to be measured acts directly on the external electrodes 105, 108. Numerous disadvantages are associated with this. The external electrodes 105, 108 have to be covered with insulation layers in order to prevent leakage currents from arising. Moreover, electrical connections of the external electrodes 105, 108 furthermore have to be provided on the upper and lower side surfaces 106, 107, such that the surfaces 106, 107 cannot be used over the whole area for the pressure loading. The external electrodes 105, 108 comprise a metallic material, which with tenable outlay is only able to be manufactured with an inadequate flatness. The unevenness on the surfaces 106, 107 can lead to measurement inaccuracies. Moreover, under constantly occurring alternating pressure loads, the metallic external electrodes 105, 108 exhibit high wear effects that can shorten the lifetime of the pressure sensor 101.